Create 589. N-ary Tree Preorder Traversal

Author: khushi3004

589. N-ary Tree Preorder Traversal

@@ -0,0 +1,38 @@
+class Solution {
+    List<Integer> result = new ArrayList<>();
+    public List<Integer> preorder(Node root) {
+        if(root == null) return result;
+        preorderHelper(root);
+        return result;
+    }
+    
+    public void preorderHelper(Node node) {
+        if(node.children == null) return;
+        result.add(node.val);
+        for(Node child : node.children) {
+            preorderHelper(child);
+        }
+    }
+}
+
+class Solution {
+    List<Integer> result = new ArrayList<>();
+    public List<Integer> preorder(Node root) {
+        if(root == null) return result;
+        
+        Stack<Node> stack = new Stack<>();
+        stack.push(root);
+        
+        while(!stack.isEmpty()) {
+            Node curr = stack.pop();
+            result.add(curr.val);
+            //Pushing in children in reverse order
+            for(int i = curr.children.size()-1; i >= 0; i--) {
+                stack.push(curr.children.get(i));
+            }
+        }
+        
+        return result;
+    }
+    
+}}